I have the Opus 120W that I got from the MP3Car Store. I initally had a bootup issue but that was taken care of when my MB was replaced on RMA. Since the new MB I haven't had any issues but I've only used it for the past couple of weeks. I have my HD tuner mounted above the PSU and so far haven't had interference issues that I can tell.
I do have a mast antenna though but it has been cut down. Also I'm unsure which one you are looking at but mine has the P4 connection for the MB. The radio is powered by the Opus as well. Here's a pic of where mine is mounted.